Stability and change in the hippocampal place representation system
Memory formation and maintenance involve a constant tension between stability and
change. On one hand, stable representations are essential for preserving past experiences.
On the other hand, memories must remain flexible to incorporate new information and
reflect the evolving world. Thus, while memory resists interference to maintain invariance, it
must also reorganize to enhance efficiency and adapt to novel experiences.
In this lecture, I will discuss one to three studies examining this balance within the
hippocampal spatial representation system. First, regarding representational drift, spatial
representations in the hippocampus gradually change with experience. Our findings suggest
that such changes are driven more by ongoing experience than by forgetting. Second, in
exploring environmental mapping, we find that the subiculum encodes differently shaped
rooms with strikingly similar activity patterns, hinting at an invariant, latent representation of
spatial structure. Third, we investigate a flashbulb memory–like effect, observing
pronounced hippocampal activity changes following salient life events in mice.
Together, these projects illustrate how the hippocampus negotiates the trade-off between
preserving established memories and accommodating new experiences.